The cost and speed determine the success or failure of four Broadband Access Technologies (1)

Although many network access methods such as ddnleased line and ISDN have appeared in the past few years, they have not been successfully popularized due to various reasons such as cost and speed. Currently, there are many broadband access methods. Currently, you can consider four types of broadband access methods: China Telecom ADSL, FTTX + LAN (residential broadband), and Cable Modem of Cable TV (Wired connection) the four broadband access methods vary greatly in terms of installation conditions, required equipment, data transmission rate, and related fees, it directly determines that different broadband access methods are suitable for different users.

I. ADSL

1. Definition of ADSL

Asypolicric Digital Subscriber Line (asypolicric Digital Subscriber Line) because of the uplink (from the user to the telecom service provider, such as the upload action) and downlink (from the telecom service provider to the user's direction, such as the download action) bandwidth asymmetry (that is, the uplink and downlink speeds are different) is called an asymmetric digital user line. It uses the frequency division multiplexing technology to divide common telephone lines into three relatively independent channels: telephone, uplink and downlink, thus avoiding mutual interference. Generally, ADSL can provide up to 3.5Mbps uplink speed and up to 24 Mbps downlink speed without affecting normal telephone communication. According to the technical features of the ADSL Broadband Service and the user's telephone service, the two are separated in terms of service processing.

Although the maximum theoretical uplink rate of ADSL can reach 1 Mbps and the downlink rate can reach 8 Mbps, the actual rate currently provided by China Telecom for ordinary household users is mostly 512 Kbps downstream, few regions provide a speed of 1 Mbps or above. It is worth noting that the transmission rate here is the user's exclusive bandwidth, so you do not have to worry that using ADSL at the same time may slow the network speed. In addition, China Telecom often uses "acceleration" of ADSL as the propaganda focus. Everyone must understand that the "acceleration" mentioned here usually refers to the downstream speed, while the upload speed remains unchanged.

To facilitate public understanding of ADSL, communication bureaus in various regions often use some nice names, such as "super one-line communication" and "network express". In fact, these refer to the same broadband method.

2. ADSL features

1. a telephone line can be used to receive calls at the same time and transmit data.

2. Although the original telephone line is used, the data transmitted by adsl is not transmitted through the telephone switch. Therefore, no additional telephone fee is required for accessing the Internet through adsl, saving the cost.

3. The data transmission rate of adsl is automatically adjusted according to the line conditions. It transfers data as best as possible.

3. Installation conditions

ADSL can directly use existing telephone lines to transmit digital information through ADSL Modem. Therefore, all users who have installed a telephony have the basic conditions for installing ADSL. Then, the user can go to the local telecommunications Bureau to check whether the phone number can install ADSL, after receiving a positive response, you can apply for installation. (In general, China Telecom will determine whether your phone number is more than 3 kilometers away from the nearest data center. If your phone number is exceeded, you cannot install it, because ADSL will weaken as it grows ). During installation, you need to bring your own 10/100 Mb adaptive Nic, while other devices such as ADSL Modem and Divider are usually provided by China Telecom. You can also buy them in some regions.

4. network logon standards

ADSL usually provides three network logon methods:

The static IP address PPPoA is directly provided for bridging, And the ATM-based end-to-end protocol PPPoE. The Ethernet-based end-to-end protocol usually does not provide static IP addresses, but dynamically allocates network addresses to users.

The use of ADSL requires PC, ADSL Modem, 10 m \ M Adaptive Nic and virtual dialing software

ADSL is an asymmetric DSL technology. The so-called asymmetric refers to the user line's uplink rate is different from the downlink rate, the uplink rate is low, the downlink rate is high, especially suitable for the transmission of multimedia information services, such as VOD, multimedia information retrieval, and other interactive services. ADSL supports uplink speed of kbps on a copper-to-copper line ~ 1 Mbps, downlink speed 1 Mbps ~ 8 Mbps, valid transmission distance of 3 ~ Within 5 kilometers.